The present invention relates to cylinders for cross-cutting, cross-perforating, or scoring a web material, such as paper, cloth, plastic, fabric, or the like, in collators, presses and other machines. Cylinders of the type with which the present invention is concerned are provided with at least one longitudinally-extending peripheral groove which carries a blade. The blade protrudes slightly from the circumference of the knife cylinder and engages a rotary cylinrical anvil mounted for rotation about an axis parallel to the axis of rotation of the cylinder. The blade functions to either cut the web into separate sheets, to perforate the web along transverse lines to facilitate its subsequent folding and separation into sheets, or scoring.
Blades of the type in question wear out very rapidly and, in may installations, must be replaced every day or two. Since the replacement of blades requires shutting down a very large piece of equipment, it is desirable to provide means for changing the blades as quickly as possible. In the past, however, no completely satisfactory construction has been provided for accomplishig this result.
In one commercially-employed cylinder construction, the blade is clamped against a side wall of the groove by means of a clamp bar positioned by several transverse bolts. In installing the blade, it is initially positioned so that it extends slightly beyond the periphery of the cylinder and the bolts associated with the clamp bar are partially tightened. Thereafter, the cylinder is rotated to bring the blade into contact with the rotary anvil. This contact shifts the blade into its correct position. The blade is then locked in this position by tightening the clamping bolts.
In a second construction, a wedge-shaped clamp bar is mounted in the groove and set screws, or bolts, which can be turned from the periphery of the clamp bar, are turned to force the clamp bar against the blade to wedge the blade against a side wall of the groove. Blades are installed in this modified design in the same manner described above.
In a third commercial form of cylinder, an accurately dimensioned blade is employed which has a cutting edge parallel to the bottom edge of the blade. In this embodiment, the bottom edge of the blade rests against a shoulder on a clamping block. In this arrangement the height of the blade is set automatically, eliminating the need for adjustment by rotation of the knife cylinder. This embodiment, however, still requires manipulation of a plurality of clamping bolts to secure the blade in position.
The principal difficulty with each of the embodiments described above is that they require an inordnate amount of time, i.e., from 3-5 minutes, to replace a blade. Other constructions have been proposed for mounting blades to effect a more rapid release. However, these constructions have the disadvantage that they are either unduly complex or are unsuited for the type of equipment with which the present cylinder construction is used.
Thus, for example, Thomas et al U.S. Pat. No. 4,594,928 discloses a knife cylinder in which the blades are clamped in position by means of a mounting member which presses the blades against a side wall of a groove in the knife cylinder. The knives are held in place by a link which is in turn engaged by a pressure cylinder.
Hornung U.S. Pat. No. 3,769,868 discloses a rotary cutting blade which is held in place by a mounting block biased toward the blade by means of expandable tubes subjected to pneumatic pressure.
Other blade-mounting construction are shown in several prior art patents. For example, Bombard U.S. Pat. No. 2,341,503 discloses a blade which is frictionally held in place by a plurality of spring-biased bores.
Walde U.S. Pat. No. 4,187,753 and Bishop U.S. Pat. No. 3,705,526 disclose rotary knife blade-mounting constructions in which the blades are held in position by compressible pads or chocks mounted on studs parallel to the plane of the blade.
Sybertz U.S. Pat. No. 3,865,164 discloses a blade mounting for a wood comminuting machine. The blade is retained in a slot by cooperating wedges, one of which is spring-biased. The blade is secured by a plurality of mounting screws to one of the wedges, requiring that these screws be loosened to replace the blade.
Humbert U.S. Pat. No. 3,989,077 discloses a rotary knife-mounting construction in which the knife is held in place by means of a permanent magnet.
Obenshain U.S. Pat. No. 3,822,625 discloses a rotary knife blade which is frictionally held in a block which carries a plurality of clamping screws which must be turned to replace a blade.
Rann U.S. Pat. No. 4,392,402 discloses a rotary knife blade-mounting construction in which the blade is held in place by wedge-shaped retaining members which are bolted to the drum.